NOMENCLATUREChapter 2

H2OH2O

molecular empirical

C6H12O6 CH2O

O3 O

N2H4 NH2

Chemical Formulas• Formula Unit:

• Identifies exact number of atoms in an ionic compound

• Molecular formula: • Identifies exact number of atoms in a covalent molecule

• Empirical formula:• Shows the simplest whole number ratio of atoms in a

compound

DIATOMIC ELEMENTS

Some elements do not like to be alone…

so they bond to themselves!

7HOFBrINCl

The ionic compound NaCl

Ionic Compounds• consist of a combination of cations and anions formed from a transfer of electrons• the formula unit is always identical to the empirical formula• the sum of the charges on the cation(s) and anion(s) in

each formula unit must equal zero

NAMING BINARY IONIC COMPOUNDS

RULE 1Metal – Nonmetal

1. Write the metal (positive ion) first

2. Change the ending of the second word to -ide

Rule 1 Examples

1. KBr

2. CaBr2

3. LiF

4. Li2O

5. MgO

6. BaS

7. K3P

8. Na3N

1. Potassium Bromide2. Calcium Bromide3. Lithium Fluoride4. Lithium Oxide5. Magnesium Oxide6. Barium Sulfide7. Potassium Phosphide8. Sodium Nitride

NAMING COMPOUNDS WITH POLYATOMICS

RULE 2Polyatomic Ions

1. DO NOT CHANGE ANYTHING!

2. When you have NH4 and a single element, change the second word to -ide

Rule 2 Examples

1. Ba(SO4)

2. Ba(SO3)

3. Na2(CO3)

4. Na(HCO3)

5. (NH4)3(PO4)

6. (NH4)(OH)

1. Barium Sulfate2. Barium Sulfite3. Sodium Carbonate4. Sodium Bicarbonate5. Ammonium Phosphate6. Ammonium Hydroxide

Al2O3

2 x +3 = +6 3 x -2 = -6

Al3+ O2-

Ca Br2

1 x +2 = +2 2 x -1 = -2

Ca2+ Br-

Na2CO3

1 x +2 = +2 1 x -2 = -2

Na+ CO32-

Formula of Ionic Compounds

NAMING COMPOUNDS WITH TRANSITION METALS

RULE 3Transition Metals

1. Can have more than one type of charge

2. Write the charge number in roman numerals

Rule 3 Examples

1. Cu2O

2. CuO

3. FeCl24. FeCl35. SnCl46. Mn2O3

7. PbS

1. Copper (I) Oxide2. Copper (II) Oxide3. Iron (II) Chloride4. Iron (III) Chloride5. Tin (IV) Chloride6. Manganese (III) Oxide7. Lead (II) Sulfide

NAMING HYDRATES

• What is a hydrate?

• Hydrates are named:

Compound • Prefix-Hydrate

FeCl3 • 6H2O = Iron (III) Chloride Hexahydrate

Name to Formula – Criss Cross Rule

1. Lithium Fluoride

2. Sodium Sulfide

3. Aluminum Bromide

4. Iron (III) Oxide

5. Carbonic Acid

6. Calcium Carbonate

7. Magnesium Acetate

8. Copper (II) Sulfate Pentahydrate

9. Ammonium Sulfite

10. Barium Hypochlorite

Covalent Compounds

• Referred to as molecules• Consists of nonmetals covalently bonded

• nonmetals or nonmetals + metalloids• Least electronegative element is usually written first

NAMING COVALENT COMPOUNDS

RULE 4Nonmetal – Nonmetal

USE PREFIXES!

1. Change the ending of the second word to -ide

2. No mono on the first word

3. Drop any double vowels

NO2 nitrogen dioxide

N2O dinitrogen monoxide

TOXIC!

Laughing Gas

PrefixesNumber of Atoms Prefixes

1

2

3

4

5

6

7

8

9

10

Rule 4 Examples1. CO

2. CO2

3. SO2

4. SO3

5. N2H4

6. N2O3

7. PCl38. SiO2

9. P2O5

10. CS2

11. Al2O3

1. Carbon Monoxide2. Carbon Dioxide3. Sulfur Dioxide4. Sulfur Trioxide5. Dinitrogen Tetrahydride6. Dinitrogen Trioxide7. Phosphorus Trichloride8. Silicon Dioxide9. Diphosphorus Pentoxide10. Carbon Disulfide11. Aluminum Oxide

ACIDS• a substance that yields hydrogen ions (H+) when dissolved in water.

• example: hydrochloric acid refers to a water solution of the molecular compound hydrogen chloride, HCl

• Many polyatomic ions are produced by the loss of hydrogen ions from oxyacids.

Acid Name: Polyatomic Ion: 24SO

3NO

34PO

sulfuric acid H2SO4 sulfatenitric acid HNO3 nitratephosphoric acid H3PO4 phosphate

NAMING ACIDS

• Binary acids: consist of two elements, usually hydrogen and a halogen

• “HX”

• Oxyacids: contain hydrogen and a polyatomic ion (usually oxygen and a third nonmetallic element)

• “HXO”

NaOH sodium hydroxide

KOH potassium hydroxide

Ba(OH)2 barium hydroxide

NAMING BASES

• Base: a substance that yields hydroxide ions (OH-) when dissolved in water.